# 0508. Most Frequent Subtree Sum

<https://leetcode.com/problems/most-frequent-subtree-sum>

## Description

Given the `root` of a binary tree, return the most frequent **subtree sum**. If there is a tie, return all the values with the highest frequency in any order.

The **subtree sum** of a node is defined as the sum of all the node values formed by the subtree rooted at that node (including the node itself).

**Example 1:**

![](https://assets.leetcode.com/uploads/2021/04/24/freq1-tree.jpg)

```
**Input:** root = [5,2,-3]
**Output:** [2,-3,4]
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2021/04/24/freq2-tree.jpg)

```
**Input:** root = [5,2,-5]
**Output:** [2]
```

**Constraints:**

* The number of nodes in the tree is in the range `[1, 104]`.
* `-105 <= Node.val <= 105`

## ac

```java
```